Sugammadex is a modified γ-cyclodextrin, with a lipophilic core and a hydrophilic periphery.

Sugammadex (designation Org 25969, trade name Bridion) is an agent for reversal of neuromuscular blockade by the agent rocuronium in general anaesthesia. It is the first selective relaxant binding agent (SRBA). This gamma cyclodextrin has been modified from its natural state by placing eight carboxyl thio ether groups at the sixth carbon positions. These extensions extend the cavity size allowing greater encapsulation of the rocuronium molecule. These negatively charged extensions electrostatically bind to the positively charged ammonium group as well as contribute to the aqueous nature of the cyclodextrin. Sugammadex's binding encapsulation of rocuronium is one of the strongest among cyclodextrins and their guest molecules. The rocuronium molecule (a modified steroid) bound within Sugammadex's lipophilic core, is rendered unavailable to bind to the acetylcholine receptor at the neuromuscular junction. Sugammadex sodium contains 8 recurring glucose units each with 5 asymmetric carbon atoms, in total 40 asymmetric carbon atoms for the whole molecule.
The Sugammadex was disclosed in U.S. Pat. No. 6,670,340 by Akzo Nobel. The process for preparing Sugammadex is there outlined as follows: (Scheme-I)

In above process step-1 involves the preparation of Vilsmeier Hack reagent by the reaction of DMF, triphenylphosphine and Iodine. Drawback associated with this step is formation of triphenylphosphine oxide as a byproduct. Removal of triphenylphosphine oxide is very difficult from the reaction; it requires repeated washing with DMF under argon atmosphere and leads to inconsistency in yield of final product. Due to this, process is lengthy and not feasible on commercial scale.
The present invention provides improved conditions for carrying out step-1 in the above scheme, whereby the product of step-1 is obtained in better purity and yield than has previously been possible.